1. Technical Field
The present invention relates generally to a cap for luer of a medical container, and more specifically to a tip cap for a syringe luer interface that reduces the removal force of the cap from the syringe luer interface.
2. Background Prior Art
Syringe bodies have been typically manufactured of glass. The glass syringe bodies are initially manufactured in a production plant. The syringe bodies are then packaged and shipped to a pharmaceutical plant where they are unpackaged, filled, sealed tightly, and sterilized. Finally, the syringe bodies are repackaged and ready to be delivered to the end user. This process is inefficient and costly.
Recently, syringe bodies have been manufactured from polymeric resins. The polymeric syringe bodies replaced the glass syringe bodies which were costly to produce and caused difficulties during the manufacturing process because the glass would chip, crack, or break. The broken glass particles would not only become hazards to workers and manufacturing equipment, but could also become sealed within the glass syringe body causing a potential health hazard to a downstream patient.
U.S. Pat. No. 6,065,270 (the ""270 patent), issued to Reinhard et al. and assigned to Schott Glaswerke of Germany, describes a method of producing a prefilled, sterile syringe body from a cyclic olefin copolymer (COC) resin. A COC polymer is useful in the manufacture of syringe bodies because it is generally clear and transparent. COC resins are, for example, disclosed in U.S. Pat. No. 5,610,253 which is issued to Hatke et al. and assigned to Hoechst Akteiengesellschaft of Germany.
The ""270 patent includes a method of manufacturing a filled plastic syringe body for medical purposes. The syringe body comprises a barrel having a rear end which is open and an outlet end with a head molded thereon and designed to accommodate an injection element, a plunger stopper for insertion into the rear end of the barrel to seal it, and an element for sealing the head. The method of manufacturing the syringe body includes the steps of: (1) forming the syringe body by injection molding a material into a core in a cavity of an injection mold, the mold having shape and preset inside dimensions; (2) opening the mold and removing the formed syringe body, said body having an initial temperature; (3) sealing one end of the barrel of the plastic syringe body; (4) siliconizing an inside wall surface of the barrel of the plastic syringe body immediately after the body is formed and while the body remains substantially at said initial temperature; (5) filling the plastic syringe body through the other end of the barrel of the plastic syringe body; and (6) sealing the other end of the barrel of the plastic syringe body, wherein the method is carried out in a controlled environment within a single continuous manufacturing line. According to the method of the ""270 patent, the sterilization step is applied to the filled and completely sealed ready-to-use syringe body. Historically, sterilization of finished syringe components (barrel, plunger, and tip cap) has been conducted using ethylene oxide, moist-heat or gamma irradiation.
The luer tip of the syringe body typically includes a stopper mounted over the tip at the distal end of the syringe barrel to prevent leakage of the contents of the syringe body and to avoid contamination therein. Typically, the stopper comprises a tip cap that provides a positive sealing engagement mechanism for the luer tip of the syringe body.
Generally, the tip of the syringe body has an exterior geometry having a sloped outer wall. Accordingly, prior art tip caps are generally manufactured with an interior cavity having a reverse sloped inner wall that mates with the sloped outer wall of the tip of the syringe body (See FIG. 1). Typically, the sloping inner diameter of the cavity of the tip cap is slightly smaller than the sloping outer diameter of the outer wall of the tip of the syringe body to provide a line-type interference fit. Specifically, at the distal end of the tip of one typical syringe body the outer diameter is 4.0 mm, and the mating interior diameter of the corresponding prior art tip cap shown in FIG. 1 is 3.4 mm. This line-type of interference fit is provided to produce the positive sealing engagement thought to be desired between the tip cap and the syringe tip in the prior art devices. However, because of the geometry of the mating syringe tip and tip cap, during removal the Poisson Ration effect occurs. This lateral contraction, in addition to the line-type interference fit sometimes resulted in undesirable contact and removal forces. Additionally, in extreme cases, the increased contact and removal forces due to the line-type interference fit led to failure of the tip cap adjacent the internal protrusion thereof.
Other types of tip caps for syringes are known in the art. U.S. Pat. No. 6,190,364 (the ""364 patent), issued to Imbert and assigned to Becton, Dickson and Company, describes another prior art tip cap for securely sealing the tip of a hypodermic syringe barrel. As shown in FIG. 1 of the ""364 patent, referenced as FIG. 2 wherein, the tip cap 154 of the ""364 patent comprises two components: an inner cap 156 and an outer cap 158. The inner cap 156 is manufactured of an elastomeric material and frictionally and/or resiliently engages portions of the syringe tip for sealing the passage through the tip. The outer cap 158 is manufactured of a rigid material which protectively encloses the inner cap. The tip cap 154 of the ""364 patent does not itself engage and secure the tip of the syringe barrel, but rather additionally requires a separate mounting collar 144. Thus, the mounting collar 144 engages the syringe tip and is also adapted to have the tip cap 154 secured thereto.
The present invention provides a tip cap with a reduced removal force when being removed from a luer tip. The tip cap comprising a body having an outer surface, a proximal end, a distal end, and an inner surface extending into the body at the proximal end to define a cavity. An annular ridge extends radially into the cavity from the inner surface of the body. When connected to the luer tip, the annular ridge defines a contact area to engage the luer tip, as well as a seal area between the tip cap and the luer tip. Additionally, the contact area of the annular ridge decreases the surface area of contact between the tip cap and the luer tip.
According to another aspect of the present invention, a plurality of annular ridges extend radially into the cavity from the inner surface of the body.
According to another aspect of the present invention, the body of the tip cap, including the annular ridges, is a unitary element that is made as a single component.
According to another aspect of the present invention, a removable tip cap is provided for a luer of a polymeric medical solution container. The tip cap has an integral body having an outer portion and a cavity extending to an inner portion. The cavity has a frustoconical inner surface and an annular ring extending from the inner surface radially toward a centerline of the tip cap. A protrusion is provided at a distal end of the cavity and is adapted to extend into a passage in the luer.
According to another aspect of the present invention, the cavity has a proximal end and a distal end. A diameter of the proximal end of the cavity is larger than a diameter of the distal end of the cavity, a diameter of the distal end of the cavity is larger than a diameter at the end of the luer, and a diameter of the proximal end of the cavity is larger than a diameter of the luer.
According to another aspect of the present invention, a removable tip cap is provided for an elongated luer tip projecting from a distal end of a fluid chamber. The tip cap has an integral body having an outer surface, a proximal end, a distal end, and a cavity extending into the body at the proximal end thereof. The tip cap further has an inner surface having a plurality of adjacent annular ridges extending radially toward a centerline of the body to define the cavity. The plurality of annular ridges defines contact areas adapted to engage the luer tip. The contact areas decrease the area of contact area between the tip cap and the luer tip, and create annular seals with the luer tip. Each of the plurality of annular ridges defines an independent seal area with the luer tip.
According to another aspect of the present invention, a removable tip cap is provided for a luer of a polymeric medical solution container. The tip cap has an integral body having an outer portion and a cavity extending adjacent a proximal end of the body to an inner portion thereof. The cavity further has a frustoconical inner surface and a plurality of annular rings extending from the inner surface radially toward a centerline of the tip cap. As such, the tip cap is adapted to removably engage the luer of the solution container.
According to another aspect of the present invention, a portion of the frustoconical inner surface of the tip cap has a surface contact area less than a surface contact area of the luer.
According to another aspect of the present invention, the annular rings provide an interference fit for securing the tip cap on the luer. Additionally, the annular rings provide for an incremental removal force during removal of the tip cap from the luer.
According to yet another aspect of the present invention, a removable tip cap is provided for a luer of a syringe. The tip cap has an integral body having an outer portion and a frustoconical cavity extending to an inner portion, and a plurality of annular ridges extending into the cavity and defining annular contact areas engaging the luer of the syringe. The annular contact areas correspond to annular areas having increased contact pressures which decreases the contact pressure between the tip cap and the luer adjacent the distal portion of the tip cap. Furthermore, the annular contact areas result in incremental removal forces due to elongation of the tip cap during removal of the tip cap from the luer.
Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following drawings.